This invention relates to a piezo-electric oscillator, and more particularly to a piezo-electric oscillator the frequency of which is adjusted by means of a capacitor.
In the past, the frequency of a crystal controlled oscillator especially for use in a wristwatch was accomplished by employing a laser to remove a portion of a thin metallic film disposed on a quartz crystal vibrator. This method was adopted in place of an adjustment method using a trimmer capacitor in order to lower costs and make more efficient use of space. However, a number of disadvantages were encountered. Specifically, once the oscillator was set to the prescribed frequency, the effects of aging, mechanical impact or supporting errors would often cause the frequency to increase. Restoring the frequency to the prescribed value using laser trimming was a difficult operation.